Question

boat wavui U
5. A driver of a car travelling at 52 km hl applies the brakes and
accelerates uniformly in the opposite direction. The car stops
in 5 s. Another driver going at 3 km h-' in another car applies
his brakes slowly and stops in 10 s. On the same graph paper
,
plot the speed versus time graphs for the two cars. Which of
the two cars travelled farther after the brakes were applied?​

Answer 1

Answer:

(A)   :         Initial speed of the car A      u=52  kmh−1=52×185=14.44  ms−1

               The car stops in 5 seconds        i.e     v=0  at  t=5

(A)   :         Initial speed of the car A      u=3  kmh−1=3×185=0.83  ms−1

               The car stops in 10 seconds        i.e     v=0  at  t=10

With the help of these initial and final points for both the cases,  we can plot the graph of speed vs time.

Area under the speed-time graph gives the distance covered.

∴   Distance covered by car A       xA=21×14.44×5=36.1 m

∴   Distance covered by car A       xB=21×0.83×10=4.15 m

Thus car A travels more distance than B.